2024, 38(5): 505-511.
doi: 10.3969/j.issn.1007-2993.2024.05.001
Abstract:
With the implementation of the carbon peaking and carbon neutrality policy, low-carbon strategies and sustainable development in the field of construction engineering have become particularly important. With the continuous development and application of the Internet of Things, artificial intelligence, BIM technology, and green materials, new sustainable development directions such as digitization, intelligence, and low-carbon have emerged in foundation pit and slope engineering. Typical cases of foundation pit and slope engineering in China in recent years were introduced, and new technologies, new processes, new equipment for green and low-carbon support and monitoring were summarized, as well as new progress in carbon emission calculation. Prospects for the new trends in the future development of foundation pit and slope engineering under the caron peaking and cabon neutrality policy were proposed.
With the implementation of the carbon peaking and carbon neutrality policy, low-carbon strategies and sustainable development in the field of construction engineering have become particularly important. With the continuous development and application of the Internet of Things, artificial intelligence, BIM technology, and green materials, new sustainable development directions such as digitization, intelligence, and low-carbon have emerged in foundation pit and slope engineering. Typical cases of foundation pit and slope engineering in China in recent years were introduced, and new technologies, new processes, new equipment for green and low-carbon support and monitoring were summarized, as well as new progress in carbon emission calculation. Prospects for the new trends in the future development of foundation pit and slope engineering under the caron peaking and cabon neutrality policy were proposed.
2024, 38(5): 512-518.
doi: 10.3969/j.issn.1007-2993.2024.05.002
Abstract:
An analytical conversion method for self-balanced test of foundation pile was proposed. The finite difference method was used to establish the control equations for each micro-section of the upper and lower piles, and the internal forces and displacements at each micro-section of the upper and lower piles can be obtained by programmed solution, which can be substituted into the exact conversion formula to convert the self-balanced test pile results into the form of the load (Q) - displacement (s) curves similar to those of the traditional static test and to solve the ultimate bearing capacity. This analytical conversion method was applied to convert the test results in conjunction with the test project of self-balanced method for three drilled piles in Yuda Wutong Court, Laibin, Guangxi. The internal forces of the three test piles all show that the soil layer closer to the loading end bears a larger load, the axial force gradually decreases from the loading end to both ends, and the change characteristics of the lateral resistances show a hyperbolic distribution. In terms of single pile bearing capacity, the simplified conversion method is conservative, while the analytical conversion method takes into account the differences in the characteristics of the soil layers on the pile side, and the accuracy can be improved by about 12% compared to the simplified conversion method. The analytical conversion method can accurately reflect the distribution law of internal force of upper and lower pile body and the bearing characteristics of soil layer on the pile side, and can efficiently and accurately realize the conversion of bearing capacity, which is widely used in the field of self-balanced test engineering of pile foundation bearing capacity.
An analytical conversion method for self-balanced test of foundation pile was proposed. The finite difference method was used to establish the control equations for each micro-section of the upper and lower piles, and the internal forces and displacements at each micro-section of the upper and lower piles can be obtained by programmed solution, which can be substituted into the exact conversion formula to convert the self-balanced test pile results into the form of the load (Q) - displacement (s) curves similar to those of the traditional static test and to solve the ultimate bearing capacity. This analytical conversion method was applied to convert the test results in conjunction with the test project of self-balanced method for three drilled piles in Yuda Wutong Court, Laibin, Guangxi. The internal forces of the three test piles all show that the soil layer closer to the loading end bears a larger load, the axial force gradually decreases from the loading end to both ends, and the change characteristics of the lateral resistances show a hyperbolic distribution. In terms of single pile bearing capacity, the simplified conversion method is conservative, while the analytical conversion method takes into account the differences in the characteristics of the soil layers on the pile side, and the accuracy can be improved by about 12% compared to the simplified conversion method. The analytical conversion method can accurately reflect the distribution law of internal force of upper and lower pile body and the bearing characteristics of soil layer on the pile side, and can efficiently and accurately realize the conversion of bearing capacity, which is widely used in the field of self-balanced test engineering of pile foundation bearing capacity.
2024, 38(5): 519-526.
doi: 10.3969/j.issn.1007-2993.2024.05.003
Abstract:
A new type of prefabricated block gravity retaining wall was proposed, which was mainly composed of cast-in-place concrete base, precast block unit, reserved grouting hole, post-insertion steel bar and cast-in-place pressure top beam, etc., and was designed from the aspects of wall precast block, interblock connection, foundation form, etc. The local stability of the new prefabricated block gravity retaining wall under earth pressure was analyzed by the finite element method, and the force failure mode, displacement characteristics and stress distribution characteristics of retaining walls with different sizes were obtained. It was concluded that the weak points of the failure of the retaining wall were located between the base and the first layer assembly. According to the finite element numerical simulation results, combined with the classical retaining wall stability calculation theory, the calculation method and process of prefabricated block gravity retaining wall stability analysis were proposed, and the rationality of the calculation method and process was verified by engineering examples.
A new type of prefabricated block gravity retaining wall was proposed, which was mainly composed of cast-in-place concrete base, precast block unit, reserved grouting hole, post-insertion steel bar and cast-in-place pressure top beam, etc., and was designed from the aspects of wall precast block, interblock connection, foundation form, etc. The local stability of the new prefabricated block gravity retaining wall under earth pressure was analyzed by the finite element method, and the force failure mode, displacement characteristics and stress distribution characteristics of retaining walls with different sizes were obtained. It was concluded that the weak points of the failure of the retaining wall were located between the base and the first layer assembly. According to the finite element numerical simulation results, combined with the classical retaining wall stability calculation theory, the calculation method and process of prefabricated block gravity retaining wall stability analysis were proposed, and the rationality of the calculation method and process was verified by engineering examples.
2024, 38(5): 527-532.
doi: 10.3969/j.issn.1007-2993.2024.05.004
Abstract:
Traditional monitoring methods are inefficient and cannot predict soil deformation in real-time and continuously with accuracy in road construction. A road automation monitoring system integrated with artificial intelligence technology was proposed. The system consists of a real-time Internet of Things (IoT) system and a data processing system. The real-time IoT system includes embedded settlement instruments with dual pressure sensors, a data acquisition system, and a network transmission system. The data processing system utilizes deep learning algorithms to train the measured data to predict soil deformation. The composition and working principles of the monitoring system was introduced. The system was validated through on-site experiments. By comparing the data from the dual pressure sensors in the embedded settlement instruments with the data from settlement plates, the results show that the error between the two is only 6.7%. This indicated that the automated monitoring instrument has high precision in road construction monitoring. On-site experimental results also prove that the deformation prediction method based on deep learning algorithms can accurately predict soil deformation during the road construction process, with a maximum prediction error of only 5.3%.
Traditional monitoring methods are inefficient and cannot predict soil deformation in real-time and continuously with accuracy in road construction. A road automation monitoring system integrated with artificial intelligence technology was proposed. The system consists of a real-time Internet of Things (IoT) system and a data processing system. The real-time IoT system includes embedded settlement instruments with dual pressure sensors, a data acquisition system, and a network transmission system. The data processing system utilizes deep learning algorithms to train the measured data to predict soil deformation. The composition and working principles of the monitoring system was introduced. The system was validated through on-site experiments. By comparing the data from the dual pressure sensors in the embedded settlement instruments with the data from settlement plates, the results show that the error between the two is only 6.7%. This indicated that the automated monitoring instrument has high precision in road construction monitoring. On-site experimental results also prove that the deformation prediction method based on deep learning algorithms can accurately predict soil deformation during the road construction process, with a maximum prediction error of only 5.3%.
2024, 38(5): 533-538.
doi: 10.3969/j.issn.1007-2993.2024.05.005
Abstract:
The underground pipe trench of ancient architectural drainage system is an important component of ancient buildings, and its function degradation is common after a long historical process. Before taking protective measures, it is necessary to conduct a functional assessment of the pipe trench. Taking the underground pipe trench of the drainage system of the Forbidden City as an example, a unit scoring method and a section method for the assessment of the pipe trench were proposed, and the specific implementation of the methods was given. The characteristics of the two methods in terms of data collection, analysis and assessment, and adaptability were compared. This provides a reference for the practice and research of the assessment of the underground pipe trench of ancient architectural drainage system.
The underground pipe trench of ancient architectural drainage system is an important component of ancient buildings, and its function degradation is common after a long historical process. Before taking protective measures, it is necessary to conduct a functional assessment of the pipe trench. Taking the underground pipe trench of the drainage system of the Forbidden City as an example, a unit scoring method and a section method for the assessment of the pipe trench were proposed, and the specific implementation of the methods was given. The characteristics of the two methods in terms of data collection, analysis and assessment, and adaptability were compared. This provides a reference for the practice and research of the assessment of the underground pipe trench of ancient architectural drainage system.
2024, 38(5): 539-547.
doi: 10.3969/j.issn.1007-2993.2024.05.006
Abstract:
Fractures in rock mass have a significant influence on the mechanical behavior, energy evolution and instability failure of rock. To clarify the rock energy evolution and instability failure mechanism of single fracture with different dip angles, based on the particle flow PFC2D method, a numerical model of sandy mudstone with single fracture with different dip angles was established, and the uniaxial compression test of sandy mudstone with single fracture with different dip angles was simulated. The results show that with the increase of single fracture dip angle, the strength and elastic modulus of sandy mudstone decrease first and then increase, and the prefabricated crack will affect the crack initiation position of the fracture surface and accelerate the formation of the fracture surface. The acoustic emission event has a small range of quiet period before the rock sample is destroyed, which can be used as a precursory criterion for rock failure. With the increase of fracture dip angle, the total energy continues to increase, and the elastic energy and dissipation energy show a trend of increasing first and then decreasing. When the dip angle is 30°, the rock sample has the weakest impact tendency, which is beneficial to reduce the risk of rock burst. When the dip angle is 90°, the rock sample has the strongest impact tendency, which is not conducive to the prevention and control of rock burst.
Fractures in rock mass have a significant influence on the mechanical behavior, energy evolution and instability failure of rock. To clarify the rock energy evolution and instability failure mechanism of single fracture with different dip angles, based on the particle flow PFC2D method, a numerical model of sandy mudstone with single fracture with different dip angles was established, and the uniaxial compression test of sandy mudstone with single fracture with different dip angles was simulated. The results show that with the increase of single fracture dip angle, the strength and elastic modulus of sandy mudstone decrease first and then increase, and the prefabricated crack will affect the crack initiation position of the fracture surface and accelerate the formation of the fracture surface. The acoustic emission event has a small range of quiet period before the rock sample is destroyed, which can be used as a precursory criterion for rock failure. With the increase of fracture dip angle, the total energy continues to increase, and the elastic energy and dissipation energy show a trend of increasing first and then decreasing. When the dip angle is 30°, the rock sample has the weakest impact tendency, which is beneficial to reduce the risk of rock burst. When the dip angle is 90°, the rock sample has the strongest impact tendency, which is not conducive to the prevention and control of rock burst.
2024, 38(5): 548-553.
doi: 10.3969/j.issn.1007-2993.2024.05.007
Abstract:
Helix Stiffened Cement Mixing Pile (HSCMP) is a new type of composite pile, and its group pile effect and bearing capacity variation law is still unclear. Based on the finite element numerical simulation method, the ratio of HSCMP pile spacing to helix diameter (Sg/DH) and the ratio of cement soil strength to soil strength around the pile (Cref/Su) were parametrically analyzed and the results were compared with the theoretical calculation of the group pile effect coefficient. The results show that the group pile bearing capacity is positively correlated with soil strength and pile spacing when the helix diameter and soil properties are kept constant; when Sg/DH≤2, the existing theoretical calculation results are similar to the numerical simulation results, and the numerical simulation results are more consistent with the stress superposition method as Sg/DH increases; when Sg/DH≤2, the stress superposition effect of soil between piles is significant, which is easy to lead to the damage of the interface of helical pile core-cement soil column, but when Cref/Su≥40, the damage mode will not be changed again, and it is shown as the damage of the interface of cement soil column-soil.
Helix Stiffened Cement Mixing Pile (HSCMP) is a new type of composite pile, and its group pile effect and bearing capacity variation law is still unclear. Based on the finite element numerical simulation method, the ratio of HSCMP pile spacing to helix diameter (Sg/DH) and the ratio of cement soil strength to soil strength around the pile (Cref/Su) were parametrically analyzed and the results were compared with the theoretical calculation of the group pile effect coefficient. The results show that the group pile bearing capacity is positively correlated with soil strength and pile spacing when the helix diameter and soil properties are kept constant; when Sg/DH≤2, the existing theoretical calculation results are similar to the numerical simulation results, and the numerical simulation results are more consistent with the stress superposition method as Sg/DH increases; when Sg/DH≤2, the stress superposition effect of soil between piles is significant, which is easy to lead to the damage of the interface of helical pile core-cement soil column, but when Cref/Su≥40, the damage mode will not be changed again, and it is shown as the damage of the interface of cement soil column-soil.
2024, 38(5): 554-559.
doi: 10.3969/j.issn.1007-2993.2024.05.008
Abstract:
Based on the laboratory test of expansive soil, the quantitative relationship between water content and shear strength index was statistically analyzed. Research shows that the shear strength index gradually decreases with the increase of water content. Compared with the internal friction angle φ, the cohesive force c is more sensitive to changes in water content. For each 5% increase in water content, cohesion c decreases by 7.5 kPa and internal friction angle φ 3° lower. On this basis, a shear strength index reduction method based on changes in water content was proposed for the design and calculation of expansive soil foundation pit support. The applicability of this method in the design of expansive soil foundation pit support was verified through engineering case calculations and on-site monitoring.
Based on the laboratory test of expansive soil, the quantitative relationship between water content and shear strength index was statistically analyzed. Research shows that the shear strength index gradually decreases with the increase of water content. Compared with the internal friction angle φ, the cohesive force c is more sensitive to changes in water content. For each 5% increase in water content, cohesion c decreases by 7.5 kPa and internal friction angle φ 3° lower. On this basis, a shear strength index reduction method based on changes in water content was proposed for the design and calculation of expansive soil foundation pit support. The applicability of this method in the design of expansive soil foundation pit support was verified through engineering case calculations and on-site monitoring.
2024, 38(5): 560-565.
doi: 10.3969/j.issn.1007-2993.2024.05.009
Abstract:
A three-dimensional finite element model was established based on the HSS constitutive model for a newly constructed shield tunnel adjacent to an existing subway project. The correctness of the numerical calculation was verified by comparing it with measured data. On this basis, further analysis was conducted on the vertical deformation characteristics of existing tunnels caused by the construction of new tunnels, as well as the influence of the two parameters of tunnel horizontal clearance and overlap angle on the deformation of existing tunnels. The results show that the calculated results of HSS model are in good agreement with the measured values, and can effectively predict the deformation of existing subway tunnel. Under the influence of the new tunnel overpassing, the existing subway tunnel has vertical uplift deformation, and the deformation mainly occurs in the range of 1.5 times the diameter of the new tunnel before the shield tunneling under-crossing to 2 times the diameter of the new tunnel after the crossing. The uplift peak point of the existing subway tunnel will shift with the second crossing of the shield, and its vertical deformation curve shows a "double peak" trend. Increasing the horizontal clearance of double track tunnels and the overlapping angle of new and old tunnels can reduce the deformation of existing tunnels.
A three-dimensional finite element model was established based on the HSS constitutive model for a newly constructed shield tunnel adjacent to an existing subway project. The correctness of the numerical calculation was verified by comparing it with measured data. On this basis, further analysis was conducted on the vertical deformation characteristics of existing tunnels caused by the construction of new tunnels, as well as the influence of the two parameters of tunnel horizontal clearance and overlap angle on the deformation of existing tunnels. The results show that the calculated results of HSS model are in good agreement with the measured values, and can effectively predict the deformation of existing subway tunnel. Under the influence of the new tunnel overpassing, the existing subway tunnel has vertical uplift deformation, and the deformation mainly occurs in the range of 1.5 times the diameter of the new tunnel before the shield tunneling under-crossing to 2 times the diameter of the new tunnel after the crossing. The uplift peak point of the existing subway tunnel will shift with the second crossing of the shield, and its vertical deformation curve shows a "double peak" trend. Increasing the horizontal clearance of double track tunnels and the overlapping angle of new and old tunnels can reduce the deformation of existing tunnels.
2024, 38(5): 566-571.
doi: 10.3969/j.issn.1007-2993.2024.05.010
Abstract:
Based on a project in the Weihe first-order terrace in Xi'an, the bearing capacity and deformation characteristics of the dense sand layer foundation were studied through field tests and numerical simulations to determine whether natural foundations for high-rise buildings of nearly 100 meters can be built in similar sites. The results show that: the P-s curve of the load test of the dense sand layer in the Weihe first-order terrace is gently variable, the characteristic value of the bearing capacity of the foundation can be 600 kPa, and the deformation modulus can be 40 MPa. The empirical coefficient ΨS can be taken as 0.2 for the calculation of foundation settlement by the sum-of-layers method for similar projects in the Weihe first-order terrace. When the geological conditions are similar, it is feasible to use natural foundations for the construction of high-rise buildings of nearly 100 meters. The results can provide a reference for the adoption of natural foundations for high-rise buildings on the Weihe first-order terrace, and also provide empirical parameters for deformation calculations on similar sites.
Based on a project in the Weihe first-order terrace in Xi'an, the bearing capacity and deformation characteristics of the dense sand layer foundation were studied through field tests and numerical simulations to determine whether natural foundations for high-rise buildings of nearly 100 meters can be built in similar sites. The results show that: the P-s curve of the load test of the dense sand layer in the Weihe first-order terrace is gently variable, the characteristic value of the bearing capacity of the foundation can be 600 kPa, and the deformation modulus can be 40 MPa. The empirical coefficient ΨS can be taken as 0.2 for the calculation of foundation settlement by the sum-of-layers method for similar projects in the Weihe first-order terrace. When the geological conditions are similar, it is feasible to use natural foundations for the construction of high-rise buildings of nearly 100 meters. The results can provide a reference for the adoption of natural foundations for high-rise buildings on the Weihe first-order terrace, and also provide empirical parameters for deformation calculations on similar sites.
2024, 38(5): 572-576.
doi: 10.3969/j.issn.1007-2993.2024.05.011
Abstract:
According to “Technical Code for Building Foundation” （DB 42/242—2014）, the recommended slope of confined water head in the flood control area of Wuhan is 0.5%～0.8%, from which the anti-floating water level in the flood control area and the confined water head of foundation pit dewatering can be approximately deduced. However, since 2003, due to the substantial shortening of the supply time on both sides of the Yangtze River and the large-scale foundation pit dewatering in urban construction, the corresponding hydraulic gradient in the flood control area has also changed greatly. Combined with the water level observation and statistical data of 40 projects in the flood control area, there is a large deviation between the measured hydraulic gradient in the control area and the recommended value of the code, and there is a non-linear attenuation relationship with the water level of the Yangtze River and the distance of the project. Through data analysis, the curve equations of peak hydraulic gradient in high water period, average hydraulic gradient in high water period and average hydraulic gradient in low water period were derived and verified by the project. The conclusion can provide reference for the revision of the code, and provide support for the selection of anti-floating water level in flood control area and dewatering of foundation pit engineering.
According to “Technical Code for Building Foundation” （DB 42/242—2014）, the recommended slope of confined water head in the flood control area of Wuhan is 0.5%～0.8%, from which the anti-floating water level in the flood control area and the confined water head of foundation pit dewatering can be approximately deduced. However, since 2003, due to the substantial shortening of the supply time on both sides of the Yangtze River and the large-scale foundation pit dewatering in urban construction, the corresponding hydraulic gradient in the flood control area has also changed greatly. Combined with the water level observation and statistical data of 40 projects in the flood control area, there is a large deviation between the measured hydraulic gradient in the control area and the recommended value of the code, and there is a non-linear attenuation relationship with the water level of the Yangtze River and the distance of the project. Through data analysis, the curve equations of peak hydraulic gradient in high water period, average hydraulic gradient in high water period and average hydraulic gradient in low water period were derived and verified by the project. The conclusion can provide reference for the revision of the code, and provide support for the selection of anti-floating water level in flood control area and dewatering of foundation pit engineering.
2024, 38(5): 577-583.
doi: 10.3969/j.issn.1007-2993.2024.05.012
Abstract:
The back mountain landslide of Bailian Temple in Ningde is a medium-sized traction type soil landslide, which is a typical landslide caused by unreasonable excavation at the foot of the slope and heavy rainfall. According to the survey results, the arc method and finite element method were used to analyze the stability of the landslide. The analysis results show that the landslide is basically stable under general conditions, and unstable - understable under rainstorm conditions. The landslide treatment adopts comprehensive measures such as slope cutting and unloading, anchor frame beams, vegetation protection, anti-slip piles, retaining walls, and setting up interception and drainage ditches. The treatment effect is good and can provide reference for similar landslide projects.
The back mountain landslide of Bailian Temple in Ningde is a medium-sized traction type soil landslide, which is a typical landslide caused by unreasonable excavation at the foot of the slope and heavy rainfall. According to the survey results, the arc method and finite element method were used to analyze the stability of the landslide. The analysis results show that the landslide is basically stable under general conditions, and unstable - understable under rainstorm conditions. The landslide treatment adopts comprehensive measures such as slope cutting and unloading, anchor frame beams, vegetation protection, anti-slip piles, retaining walls, and setting up interception and drainage ditches. The treatment effect is good and can provide reference for similar landslide projects.
2024, 38(5): 584-591.
doi: 10.3969/j.issn.1007-2993.2024.05.013
Abstract:
The stress path of soil is closely tied to deformation during dynamic tunnel excavation. A three-dimensional model of tunnel construction was created using the FLAC3D finite difference software. The double-side wall guide pit method was used to simulate the excavation process of a large-section tunnel and measure the resulting soil stress state. The changing laws of the stress state were then investigated based on the numerical simulation results. Indoor triaxial tests were conducted on soil reinforced with fly ash cement under different stress paths to replicate the stress and deformation of soil units during tunnel excavation and unloading. Unreinforced soil specimens were used as a control group. The numerical simulations and laboratory test results reveal that the stress paths of the surrounding rock unit soil at monitoring points are complex, and can be roughly divided into two categories: the process of constant confining pressure unloading axial pressure and constant confining pressure rising axial pressure. The cement-reinforced specimens showed less deformation and no signs of failure, while the unreinforced specimens were damaged during the stress path tests of different soil positions within the simulated surrounding rock unit.
The stress path of soil is closely tied to deformation during dynamic tunnel excavation. A three-dimensional model of tunnel construction was created using the FLAC3D finite difference software. The double-side wall guide pit method was used to simulate the excavation process of a large-section tunnel and measure the resulting soil stress state. The changing laws of the stress state were then investigated based on the numerical simulation results. Indoor triaxial tests were conducted on soil reinforced with fly ash cement under different stress paths to replicate the stress and deformation of soil units during tunnel excavation and unloading. Unreinforced soil specimens were used as a control group. The numerical simulations and laboratory test results reveal that the stress paths of the surrounding rock unit soil at monitoring points are complex, and can be roughly divided into two categories: the process of constant confining pressure unloading axial pressure and constant confining pressure rising axial pressure. The cement-reinforced specimens showed less deformation and no signs of failure, while the unreinforced specimens were damaged during the stress path tests of different soil positions within the simulated surrounding rock unit.
2024, 38(5): 592-597.
doi: 10.3969/j.issn.1007-2993.2024.05.014
Abstract:
Combining the common bonding slip phenomena in natural faults with the characteristics of granular materials, indoor direct shear tests and discrete element numerical analysis using glass bead particles were conducted. By changing the normal stress, shear rate, and particle size, the influence of loading conditions and particle size on the stick-slip characteristics of granular materials were investigated. Model experiments and numerical simulations indicate that glass bead particles exhibit periodic stick-slip under shear conditions, and the frictional healing and stick-slip period are key parameters characterizing the stick-slip characteristics of particles. The frictional healing decreases with increasing shear rate and increases with increasing particle diameter, while the normal stress has a smaller impact on the frictional healing. Stick-slip period and frictional healing show a positive correlation, with the stick-slip period significantly decreasing with increasing shear rate. The frictional interlocking between particles is an important factor influencing stick-slip behavior.
Combining the common bonding slip phenomena in natural faults with the characteristics of granular materials, indoor direct shear tests and discrete element numerical analysis using glass bead particles were conducted. By changing the normal stress, shear rate, and particle size, the influence of loading conditions and particle size on the stick-slip characteristics of granular materials were investigated. Model experiments and numerical simulations indicate that glass bead particles exhibit periodic stick-slip under shear conditions, and the frictional healing and stick-slip period are key parameters characterizing the stick-slip characteristics of particles. The frictional healing decreases with increasing shear rate and increases with increasing particle diameter, while the normal stress has a smaller impact on the frictional healing. Stick-slip period and frictional healing show a positive correlation, with the stick-slip period significantly decreasing with increasing shear rate. The frictional interlocking between particles is an important factor influencing stick-slip behavior.
2024, 38(5): 598-604.
doi: 10.3969/j.issn.1007-2993.2024.05.015
Abstract:
In response to the mechanical characteristics of the residual soil of granite in Youxi, Fujian, which is prone to softening and disintegration when encountering water, the external additives mixing method was used to improve its properties by adding additives to reduce its permeability coefficient. Adding ratios of lime, fly ash, and residual soil were set to 1∶1∶8, 1∶2∶7, and 1∶3∶6, respectively. Basic physical property index tests, compaction tests, and particle grading analysis tests were conducted on the granite residual soil from Youxi in Fujian. Variable water head permeability tests were conducted on the granite residual soil and improved granite residual soils separately. The test results showed that: (1) The saturated permeability coefficients of the improved granite residual soils by adding lime and fly ash into soil were decreased remarkably compared with that of the remolded residual soil, and its impermeability has been improved. (2) When the ratio of lime, ash, and soil is 1∶2∶7, the decrease in saturated permeability coefficient is the greatest, and the improvement effect in permeability is the best. (3) Whether remolded soil or improved soil, its saturated permeability coefficient increases with the increasing of its pore ratio, and decreases with the increasing of its dry density.
In response to the mechanical characteristics of the residual soil of granite in Youxi, Fujian, which is prone to softening and disintegration when encountering water, the external additives mixing method was used to improve its properties by adding additives to reduce its permeability coefficient. Adding ratios of lime, fly ash, and residual soil were set to 1∶1∶8, 1∶2∶7, and 1∶3∶6, respectively. Basic physical property index tests, compaction tests, and particle grading analysis tests were conducted on the granite residual soil from Youxi in Fujian. Variable water head permeability tests were conducted on the granite residual soil and improved granite residual soils separately. The test results showed that: (1) The saturated permeability coefficients of the improved granite residual soils by adding lime and fly ash into soil were decreased remarkably compared with that of the remolded residual soil, and its impermeability has been improved. (2) When the ratio of lime, ash, and soil is 1∶2∶7, the decrease in saturated permeability coefficient is the greatest, and the improvement effect in permeability is the best. (3) Whether remolded soil or improved soil, its saturated permeability coefficient increases with the increasing of its pore ratio, and decreases with the increasing of its dry density.
2024, 38(5): 605-610.
doi: 10.3969/j.issn.1007-2993.2024.05.016
Abstract:
The accumulation of construction waste soil has occupied a large amount of land resources and result in environmental pollution. A new curing agent, NB01, was adopted to solidify typical construction waste soil in Ningbo. Through conducting a series of macro-micro laboratory tests such as unconfined compressive strength test, road performance test, X-ray diffraction test, and electron microscopy scanning test, the solidification effect of NB01 solidified construction waste soil roadbed filler was investigated, and the mechanism of NB01 solidified construction waste soil was further revealed. The test results show that the unconfined compression strength, qu, of solidified muck increases with the increase of curing age and content. After 28-day curing, qu of the solidified muck can reach 1396 kPa, the water stability coefficient of the solidified soil approaches to 0.96, and the CBR value is larger than 25.80%, which meets the performance requirements of subgrade filler. The hydration reaction of NB01 can produce C-A-H and C-S-H gel, which enhance the cementation between soil particles and fill the pores and further promote the mechanical properties of solidified construction waste soil. The study could provide guidance for the recycling and utilization of construction waste resources.
The accumulation of construction waste soil has occupied a large amount of land resources and result in environmental pollution. A new curing agent, NB01, was adopted to solidify typical construction waste soil in Ningbo. Through conducting a series of macro-micro laboratory tests such as unconfined compressive strength test, road performance test, X-ray diffraction test, and electron microscopy scanning test, the solidification effect of NB01 solidified construction waste soil roadbed filler was investigated, and the mechanism of NB01 solidified construction waste soil was further revealed. The test results show that the unconfined compression strength, qu, of solidified muck increases with the increase of curing age and content. After 28-day curing, qu of the solidified muck can reach 1396 kPa, the water stability coefficient of the solidified soil approaches to 0.96, and the CBR value is larger than 25.80%, which meets the performance requirements of subgrade filler. The hydration reaction of NB01 can produce C-A-H and C-S-H gel, which enhance the cementation between soil particles and fill the pores and further promote the mechanical properties of solidified construction waste soil. The study could provide guidance for the recycling and utilization of construction waste resources.
2024, 38(5): 611-617.
doi: 10.3969/j.issn.1007-2993.2024.05.017
Abstract:
To eliminate the defects of traditional backfilling methods and materials, combined with the characteristics of collapsible loess area, the premixed fluidized solidified soil with collapsible loess and gravel as aggregate was prepared. The influence of different loess-to-gravel (L/G), water-to-solid (W/S) and binder-to-aggregate (B/A) ratios on the workability and mechanical properties of the premixed fluid solidified soil was analyzed by carrying out flowability and unconfined compressive strength tests. The permeability test and collapsibility test were conducted to discuss the performance change of the proposed material after solidification and water exposure. The main conclusions are as follows: (1) For certain fixed cementitious material content, with the increase of collapsible loess content, the amount of water required to meet the flowability requirements of the mixture also increases, but the strength of the sample decreases as a whole. (2) The increase of the content of cementitious materials improves the strength of the sample, but reduces the flowability of the mixture, especially for the mixture with large L/G ratio and relatively low W/S ratio. (3) Premixed fluidized solidified soil made with collapsible loess and gravel which meets the requirements of flowability and minimum strength also meets the requirements of impermeability and collapsibility in the relevant specifications. (4) According to the test results, after W/S ratio is adjusted to meet the flowability requirement, the fluidized premixed solidified soil with L/G ratio between 1.50 and 1.86 and B/A ratio not less than 0.06 has good workability and mechanical properties.
To eliminate the defects of traditional backfilling methods and materials, combined with the characteristics of collapsible loess area, the premixed fluidized solidified soil with collapsible loess and gravel as aggregate was prepared. The influence of different loess-to-gravel (L/G), water-to-solid (W/S) and binder-to-aggregate (B/A) ratios on the workability and mechanical properties of the premixed fluid solidified soil was analyzed by carrying out flowability and unconfined compressive strength tests. The permeability test and collapsibility test were conducted to discuss the performance change of the proposed material after solidification and water exposure. The main conclusions are as follows: (1) For certain fixed cementitious material content, with the increase of collapsible loess content, the amount of water required to meet the flowability requirements of the mixture also increases, but the strength of the sample decreases as a whole. (2) The increase of the content of cementitious materials improves the strength of the sample, but reduces the flowability of the mixture, especially for the mixture with large L/G ratio and relatively low W/S ratio. (3) Premixed fluidized solidified soil made with collapsible loess and gravel which meets the requirements of flowability and minimum strength also meets the requirements of impermeability and collapsibility in the relevant specifications. (4) According to the test results, after W/S ratio is adjusted to meet the flowability requirement, the fluidized premixed solidified soil with L/G ratio between 1.50 and 1.86 and B/A ratio not less than 0.06 has good workability and mechanical properties.
2024, 38(5): 618-623.
doi: 10.3969/j.issn.1007-2993.2024.05.018
Abstract:
Because of the soil skeleton containing dominant silt as well as interparticle cementation, the natural loess behaves in a structured way. To study the influence of structural properties on the small-strain stiffness of loess, resonant column tests were performed on typical natural and remolded loess under different confining pressures. The results showed that both the original and remolded loess exhibit a nonlinear stiffness characteristic within the small strain range and their shear modulus-shear strain (G-γ) relationships can be fitted by the Hardin-Drnevich hyperbolic model. Structural properties were found to significantly control the small-strain stiffness properties of loess, as exemplified by a higher shear modulus and a lower sensitivity of the maximum shear modulus to confining pressure of natural loess compared to the case of remolded soil. In addition, this study quantified the effect of structure on the small strain stiffness of loess and makes comparisons with some well-studied sands and clays (including London clay and Ottawa sand). This research enhanced the understanding of the mechanical behavior of structured loess and can provide technical reference for related engineering design.
Because of the soil skeleton containing dominant silt as well as interparticle cementation, the natural loess behaves in a structured way. To study the influence of structural properties on the small-strain stiffness of loess, resonant column tests were performed on typical natural and remolded loess under different confining pressures. The results showed that both the original and remolded loess exhibit a nonlinear stiffness characteristic within the small strain range and their shear modulus-shear strain (G-γ) relationships can be fitted by the Hardin-Drnevich hyperbolic model. Structural properties were found to significantly control the small-strain stiffness properties of loess, as exemplified by a higher shear modulus and a lower sensitivity of the maximum shear modulus to confining pressure of natural loess compared to the case of remolded soil. In addition, this study quantified the effect of structure on the small strain stiffness of loess and makes comparisons with some well-studied sands and clays (including London clay and Ottawa sand). This research enhanced the understanding of the mechanical behavior of structured loess and can provide technical reference for related engineering design.
2024, 38(5): 624-630.
doi: 10.3969/j.issn.1007-2993.2024.05.019
Abstract:
To study the influence of water and disturbance on the strength and deformation of weak-expansive soil in the Hefei area, the undisturbed samples and saturated disturbed samples of weak-expansive soil in the deep foundation pit of Huifu Road Station of Hefei Metro Line 7 were subjected to conventional saturated triaxial compression (CTC) and triaxial tension (CTE) under three confining pressures of 50 kPa, 100 kPa and 200 kPa, and the undisturbed non-immersed samples were subjected to a triaxial compression test. By comparing the differences of stress-strain, strength index, and deformation modulus between undisturbed and saturated disturbed samples, the influence of saturated disturbance on the mechanical properties of expansive soil was discussed, and the mineral composition and content of expansive soil were tested by XRD diffraction. The test results show that: (1) The soil of the foundation pit of Hefei Metro Line 7 is cohesive weak expansive soil, and the montmorillonite content in clay minerals accounts for 46%. (2) The decrease of cohesion mainly manifests the decrease of strength of Hefei weak-expansive soil. The cohesion of the undisturbed sample is 56% lower than that of the disturbed saturated remolded sample, while the friction angle change is insignificant. (3) The weak-expansive soil in the foundation pit of Hefei Metro Line 7 has the phenomenon of over-consolidation, characterized by the dilatancy softening of the undisturbed sample. (4) The initial modulus of Hefei weak-expansive soil decreased by about 20% after water disturbance, and water infiltration significantly reduced the deformation resistance of expansive soil.
To study the influence of water and disturbance on the strength and deformation of weak-expansive soil in the Hefei area, the undisturbed samples and saturated disturbed samples of weak-expansive soil in the deep foundation pit of Huifu Road Station of Hefei Metro Line 7 were subjected to conventional saturated triaxial compression (CTC) and triaxial tension (CTE) under three confining pressures of 50 kPa, 100 kPa and 200 kPa, and the undisturbed non-immersed samples were subjected to a triaxial compression test. By comparing the differences of stress-strain, strength index, and deformation modulus between undisturbed and saturated disturbed samples, the influence of saturated disturbance on the mechanical properties of expansive soil was discussed, and the mineral composition and content of expansive soil were tested by XRD diffraction. The test results show that: (1) The soil of the foundation pit of Hefei Metro Line 7 is cohesive weak expansive soil, and the montmorillonite content in clay minerals accounts for 46%. (2) The decrease of cohesion mainly manifests the decrease of strength of Hefei weak-expansive soil. The cohesion of the undisturbed sample is 56% lower than that of the disturbed saturated remolded sample, while the friction angle change is insignificant. (3) The weak-expansive soil in the foundation pit of Hefei Metro Line 7 has the phenomenon of over-consolidation, characterized by the dilatancy softening of the undisturbed sample. (4) The initial modulus of Hefei weak-expansive soil decreased by about 20% after water disturbance, and water infiltration significantly reduced the deformation resistance of expansive soil.
2017, 31(3): 153-159,163.
doi: 10.3969/j.issn.1007-2993.2017.03.010
摘要：
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
2020, 34(3): 143-149.
doi: 10.3969/j.issn.1007-2993.2020.03.005
摘要：
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
2016, 30(2): 85-88.
doi: 10.3969/j.issn.1007-2993.2016.02.007
摘要：
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
2016, 30(1): 6-11.
doi: 10.3969/j.issn.1007-2993.2016.01.002
摘要：
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
2016, 30(1): 12-19,38.
doi: 10.3969/j.issn.1007-2993.2016.01.003
摘要：
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
3D Laser Scanning Technology and BIM Technology in Ancient Building Protection Surveying and Mapping
2019, 33(4): 222-225.
doi: 10.3969/j.issn.1007-2993.2019.04.008
摘要：
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
2019, 33(2): 115-120.
doi: 10.3969/j.issn.1007-2993.2019.02.013
摘要：
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
2019, 33(2): 84-88.
doi: 10.3969/j.issn.1007-2993.2019.02.006
摘要：
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
2017, 31(6): 306-310.
doi: 10.3969/j.issn.1007-2993.2017.06.009
摘要：
以某一地下一~二层连通车库基坑设计项目为依托,在分析该基坑工程特点的基础上,介绍和分析了不同开挖深度和复杂环境条件下的多种基坑支护形式的组合应用和监测结果,为今后类似工程提供一些借鉴和参考。
以某一地下一~二层连通车库基坑设计项目为依托,在分析该基坑工程特点的基础上,介绍和分析了不同开挖深度和复杂环境条件下的多种基坑支护形式的组合应用和监测结果,为今后类似工程提供一些借鉴和参考。
2018, 32(4): 189-193,198.
doi: 10.3969/j.issn.1007-2993.2018.04.006
摘要：
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
2021, 35(1): 1-6,11.
doi: 10.3969/j.issn.1007-2993.2021.01.001
Abstract:
2021, 35(4): 269-274.
doi: 10.3969/j.issn.1007-2993.2021.04.012
Abstract:
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ISSN：1007-2993
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